Teses / dissertações sobre o tema "Nanostructures and nanocomposites"
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Kulkarni, Dhaval Deepak. "Interface properties of carbon nanostructures and nanocomposite materials". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49092.
Texto completo da fonteMahanta, Nayandeep Kumar. "Thermal Transport in Isolated Carbon Nanostructures and Associated Nanocomposites". Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1334602932.
Texto completo da fonteVenkatachalapathy, Viswanathan. "PLASMA PROCESSING FOR RETENTION OF NANOSTRUCTURES". Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4197.
Texto completo da fontePh.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science & Engr PhD
Behler, Kristopher Gogotsi IU G. "Chemically modified carbon nanostructures for electrospun thin film polymer-nanocomposites /". Philadelphia, Pa. : Drexel University, 2008. http://hdl.handle.net/1860/2920.
Texto completo da fonteKim, Kwang-Hyon. "Ultrafast nonlinear optical processes in metal-dielectric nanocomposites and nanostructures". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://dx.doi.org/10.18452/16495.
Texto completo da fonteThis work reports results of a theoretical study of nonlinear optical processes in metal-dielectric nanocomposites used for the increase of the nonlinear coefficients and for plasmonic field enhancement. The main results include the study of the transient saturable nonlinearity in dielectric composites doped with metal nanoparticles, its physical mechanism as well its applications in nonlinear optics. For the study of the transient response, a time-depending equation for the dielectric function of the nanocomposite using the semi-classical two-temperature model is derived. By using this approach, we study the transient nonlinear characteristics of these materials in comparison with preceding experimental measurements. The results show that these materials behave as efficient saturable absorbers for passive mode-locking of lasers in the spectral range from the visible to near IR. We present results for the modelocked dynamics in short-wavelength solid-state and semiconductor disk lasers; in this spectral range other efficient saturable absorbers do not exist. We suggest a new mechanism for the realization of slow light phenomenon by using glasses doped with metal nanoparticles in a pump-probe regime near the plasmonic resonance. Furthermore, we study femtosecond plasmon generation by mode-locked surface plasmon polariton lasers with Bragg reflectors and metal-gain-absorber layered structures. In the final part of the thesis, we present results for high-order harmonic generation near a metallic fractal rough surface. The results show a possible reduction of the pump intensities by three orders of magnitudes and two orders of magnitudes higher efficiency compared with preceding experimental results by using bow-tie nanostructures.
Khanadeev, V. A., B. N. Khlebtsov, G. S. Terentyuk, D. S. Chumakov, M. V. Basko, A. B. Bucharskaya, E. A. Genina, A. N. Bashkatov e N. G. Khlebtsov. "Mesoporous Silica and Composite Nanostructures for Theranostics". Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35481.
Texto completo da fonteAbdelaaziz, Muftah Ali. "Synthesis of nanocomposites with nano-TiO2 particles and their applications as dental materials". Thesis, Cape Peninsula University of Technology, 2012. http://hdl.handle.net/20.500.11838/1534.
Texto completo da fonteA study of the modification of dental nanocomposites with nanosized fillers is presented. The incorporation of TiO2 (titania) nanoparticles, via a silane chemical bond, to a standard dental acrylic resin matrix was explored to determine whether there was an increase in the wear resistance, flexural strength and surface hardness properties of the dental nanocomposites. The principal aim of this study was to synthesize dental nanocomposites with different sizes, treated, nano-TiO2 fillers in urethane dimethacrylate (UDMA) for potential application in posterior restoration and to evaluate their mechanical properties. Treatment of the nano-TiO2 particles was carried out with a silane coupling agent, 3-(methacryloyloxy)propyltrimethoxysilane (MPTMS), to improve bonding between the nano-TiO2 particles and acrylic matrix (UDMA), and reduce agglomeration of the nano-TiO2. Characterisation of products was carried out using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fourier transform infrared spectroscopy (FTIR). TEM results were used to compare the particle size distributions of untreated TiO2 and treated TiO2 under various experimental conditions in an ethanol solvent, while SEM images showed the adhesion between the matrix (UDMA) and the nano-TiO2. FTIR was used to show the qualitative composition of untreated TiO2 and treated TiO2. Eighteen groups of experimental dental nanocomposites were evaluated. Each group contained different average particle sizes of nano-TiO2 (filler): 5 nm, 21 nm and 80 nm. Each particle size category was treated with three different concentrations of the silane, (MPTMS): 2.5, 10 and 30 wt %. Samples were prepared by mixing the monomer resin matrix of UDMA and nano-TiO2 particles. For comparison, a commercially available dental resin was reinforced with untreated and treated nano-TiO2 particle sizes 5, 21 and 80 nm. Wear resistance, flexural strength and surface hardness of TiO2 nanocomposites treated with 2.5 wt % MPTMS were significantly higher compared to those treated with 10 and 30 wt% MPTMS. The nanocomposites with 5 nm TiO2 had higher wear loss, lower flexural strength and lower surface hardness values compared to those with 21 nm and 80 nm TiO2. Statistical analysis showed that the effect of the concentrations of MPTMS on wear resistance and surface hardness of specimens was significant (p<0.001), which is less than 0.05, while the effect of the concentration of MPTMS on flexural strength was statistically not significant, (p=0.02). Control composites reinforced with treated 80 nm TiO2 particles had much better mechanical properties than any of the other specimens. It was concluded that the most available commercial product for dental restorations could be improved by the addition of nano-TiO2 with relatively large particle size.
Kana, Jean Bosco Kana. "Towards stimuli-responsive functional nanocomposites : smart tunable plasmonic nanostructures Au-VO2". Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_8032_1299494958.
Texto completo da fonteThe fascinating optical properties of metallic nanostructures, dominated by collective oscillations of free electrons known as plasmons, open new opportunities for the development of devices fabrication based on noble metal nanoparticle composite materials. This thesis demonstrates a low-cost and versatile technique to produce stimuli-responsive ultrafast plasmonic nanostructures with reversible tunable optical properties. Albeit challenging, further control using thermal external stimuli to tune the local environment of gold nanoparticles embedded in VO2 host matrix would be ideal for the design of responsive functional nanocomposites. We prepared Au-VO2 nanocomposite thin films by the inverted cylindrical reactive magnetron sputtering (ICMS) known as hollow cathode magnetron sputtering for the first time and report the reversible tuning of surface plasmon resonance of Au nanoparticles by only adjusting the external temperature stimuli. The structural, morphological, interfacial analysis and optical properties of the optimized nanostructures have been studied. ICMS has been attracting much attention for its enclosed geometry and its ability to deposit on large area, uniform coating of smart nanocomposites at high deposition rate. Before achieving the aforementioned goals, a systematic study and optimization process of VO2 host matrix has been done by studying the influence of deposition parameters on the structural, morphological and optical switching properties of VO2 thin films. A reversible thermal tunability of the optical/dielectric constants of VO2 thin films by spectroscopic ellipsometry has been intensively also studied in order to bring more insights about the shift of the plasmon of gold nanoparticles imbedded in VO2 host matrix.
Xu, Chen. "Alumina based nanocomposites by precipitation". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:2bc4b631-6b5e-4536-b842-63c591df2832.
Texto completo da fonteKoh, Pei Yoong. "Deposition and assembly of magnesium hydroxide nanostructures on zeolite 4A surfaces". Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37159.
Texto completo da fonteBelchi, Raphaëlle. "Architectures à base de nanostructures de carbone et TiO₂pour le photovoltaïque". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS329/document.
Texto completo da fontePhotovoltaic is a promising renewable energy to tackle global warming and the depletion of fossil resources. The emerging field of perovskite solar cells (3rd generation photovoltaic) is very attractive because it uses abundant and easy-processing materials (low-cost technology) and provides competitive efficiencies.Still, efforts remain to be performed to develop this technology, especially concerning the improvement of efficient and reliable charge transporting electrodes. Titanium dioxide layer, commonly used for electron extraction, presents defects that limit the performance and lifetime of the perovskite solar cells.This work proposes the use of materials based on TiO₂ and carbon nanostructures to improve the electron transport and collection within the solar cells, in order to enhance the power conversion efficiency. The singular technique of laser pyrolysis, which is a continuous process of nanoparticles synthesis, was adapted to produce TiO₂/graphene nanocomposites with well-controlled properties. These materials have been characterized and integrated into perovskite solar cells that demonstrate an improved efficiency in presence of graphene.Besides, this work presents an innovating architecture based on vertically aligned carbon nanotubes for the electron collection of a perovskite solar cell. We show then the strong potential of carbon materials for optoelectronic, especially 3rd generation photovoltaic
Chunder, Anindarupa. "FABRICATION OF FUNCTIONAL NANOSTRUCTURES USING POLYELECTROLYTE NANOCOMPOSITES AND REDUCED GRAPHENE OXIDE ASSEMBLIES". Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3082.
Texto completo da fontePh.D.
Department of Chemistry
Sciences
Chemistry PhD
Bersani, Marco. "Chemical methods for the preparation of gold particles based nanostructures and nanocomposites". Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425973.
Texto completo da fonteVieitas, de Amaral Dias Ana Inês. "Plasma based assembly and engineering of advanced carbon nanostructures". Thesis, Orléans, 2018. http://www.theses.fr/2018ORLE2019/document.
Texto completo da fontePlasma environments constitute powerful tools in materials science by allowing the creation of innovative materials and the enhancement of long existing materials that would not otherwise be achievable. The remarkable plasma potential derives from its ability to simultaneously provide dense fluxes of charged particles, chemically active molecules, radicals, heat and photons which may strongly influence the assembly pathways across different temporal and space scales, including the atomic one.In this thesis, microwave plasma-based methods have been applied to the synthesis of advanced carbon nanomaterials including graphene, nitrogen-doped graphene (N-graphene) and diamond-like structures. To this end, the focus was placed on the optimization of the production processes of two-dimensional (2D) carbon nanostructures, such as graphene and N-graphene, by further elaboration and refinement of the microwave plasma-based method developed at the Plasma Engineering Laboratory (PEL). The scaling up of the synthesis process for high-quality graphene using surface-wave plasmas operating at atmospheric pressure and argon-ethanol mixtures was successfully achieved. Moreover, N-graphene was synthetized via a single-step process, by adding nitrogen to the argon-ethanol mixture, and via two-step process, by submitting previously synthetized graphene to the remote region of a low-pressure argon-nitrogen plasma. Nitrogen atoms were usefully incorporated into the hexagonal graphene lattice, mainly as pyrrolic, pyridinic and quaternary bonds. A doping level of 25% was attained.Different types of carbon nanostructures, including graphene and diamond-like nanostructures, were also produced by using methane and carbon dioxide as carbon precursors in an argon plasma.Additionally, capacitively-coupled radio-frequency plasmas have been employed in the functionalization of graphene and in the synthesis of Polyaniline (PANI)-graphene composites. The potential uses of these materials were studied, with both showing favourable characteristics for their applicability in biosensing applications
Volodin, A. A., B. P. Tarasov, A. A. Belmesov, E. V. Gerasimova, A. D. Zolotarenko e D. V. Shchur. "Electro-Conductive Composites Based on Metal Oxides and Carbon Nanostructures". Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35124.
Texto completo da fonteChoi, Han Ho. "Synthesis and chacterization [sic] of tailored zinc oxide nanostructures and their engineered nanocomposites". [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0008248.
Texto completo da fonteShi, Yupeng. "Functionalized Silica Nanostructures : Degradation Pathways and Biomedical Application from 2D to 3D". Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS122/document.
Texto completo da fonteSilica nanoparticles, thanks to the great easy and adaptability of particle synthesis and limited biotoxicity, is very widely studied for biomedical applications. This thesis conducted a large diversity of investigations involving silica nanomaterials. Firstly, the physicochemical properties and biodegradation properties of three types of structured silica nanoparticles were studied in a buffer, a culture medium and in contact with human dermal fibroblasts that suggest that, under these conditions, the silica nanoparticles must be mainly considered as degraded by hydrolysis and not biodegraded. Then, multifunctional silica nanoparticles which are consist of hollow silica nanoparticles and MnO2 nanosheets were synthesized. And the control drug release and imaging performance of this nanoplatforms were studied from 2D to 3D models. This approach could be used for a rapid assessment of the biofunctionality of nanoparticles before setting up in vivo experiments. Furthermore, a new 3D collagen-based nanocomposites using silica rods were studied and the relationships between the composite composition, structure and mechanical properties, emphasizing the key role of collagen-silica interactions. The influence of these parameters on the adhesion and proliferation of fibroblast cells was also investigated. In addition, we prepared and used magnetic silica nanorods to control particle orientation within the collagen network thanks to an external magnetic field. All the results bring new insights on the preparation and properties of bionanocomposites and open the route to multifunctional hydrogels
Georgieva, Petya. "DEVELOPMENT OF THERMALLY PROCESSED NANOCOMPOSITES WITH CONTROLLED SURFACES". Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2883.
Texto completo da fontePh.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science and Engineering
Guimaraes, de Sa Rafael. "In-situ and ex-situ incorporation of carbon nanostructures into ceramic-carbon-metal nanocomposites". Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526358.
Texto completo da fonteDo, Isabelle. "Nanocomposites nanotubes de carbone/élastomère : Propriétés rhéologiques et électriques". Pau, 2007. http://www.theses.fr/2007PAUU3005.
Texto completo da fonteSince carbon nanotubes (CNT) tend to remain as entangled agglomerates, homogeneous dispersed states within a polymer is not easily obtained, which reduces the interest of nanotubes as reinforcements. Many of the solutions proposed to address this issue rely on the modification of the interface between carbon nanotubes and the polymer matrix. The aim of the study is to establish the relationship between the nature of the CNT/polymethylacrylate (PMA) interface and the spatial organization of the CNTs in the matrix, on the one hand, and rheological and electrical properties of the nanocomposites, on the other hand. The interface is controlled by using polyacrylic acid (PAA), either by grafting it on the nanotubes surface, or by using it as a surfactant. The study of the morphology of the composites by electronic microscopy showed the importance of distinguishing the distribution of CNTs in the matrix (i. E. The repartition of the nanotubes clusters in the whole sample), from their dispersion (i. E. Their individualization within the clusters). This distinction is central as it allows explaining the physical properties of the nanocomposites. The studies of the linear viscoelastic and electrical properties of the composites highlighted the existence of percolation phenomena. We also showed that the electrical properties of the composites are sensitive to the CNTs dispersion, whereas the rheological ones are sensitive to the quality of distribution. The use of PAA, either grafted or adsorbed on nanotubes, allows an increase in electrical conductivity as well as a better dispersion of the nanotubes, thus lowering the electrical percolation thresholds
Habis, Christelle. "Development of ZnO-FTO nanocomposites for the use in transparent conductive thin films". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0192.
Texto completo da fonteMy thesis work entitled “Development of ZnO-FTO nanocomposites for the use in transparent conductive thin films” is supervised by Professor Michel Aillerie at University of Lorraine. This work was mainly made at the “Laboratoire des Matériaux Optiques, Photoniques et Systèmes” LMOPS in Centrale Supélec, Metz. Although this work forms a whole in the elaboration of transparent conductive oxides, it is divided into two parts. The first part consists on identifying the properties of bulk materials (ZnO and FTO) deposited in the form of thin film. Whereas, the second part is about the elaboration and characterization of Zinc Oxide (ZnO) and Aluminum doped Zinc Oxide (AZO) nanofibers, then associated to FTO thin films to form nanocomposite. The main objective of this work is to make flexible electrodes using low cost and abundant material, but also improving the optical properties and more specifically the haze factor of the nanocomposite layers.Transparent conductive oxides (TCOs) are technologically significant class of materials extensively used in thin film solar cells due to their ability to transmit light and collect charge carriers. In addition to the fundamental qualities of transparency and conductivity, the TCOs are frequently desired to have a certain degree of surface roughness (i.e., texture) in order to effectively scatter transmitted light into the active materials, therefore lengthen the optical path and, as a result, enhance the performance of the cell and light absorption. This thesis focuses on the development of low-cost fabrication techniques for transparent oxide layers using non-polluting materials to enable the functionalization of operational devices with high efficiency for renewable energy production. The choice was made to study tin-based TCO layers doped with fluorine, F:SnO2, known as FTOs for "Fluor Tin Oxides". FTOs are wide band gap oxides, like ZnO, TiO2, Al2O3, pure or doped. In principle, these layers have a high scattering factor, as defined above, in order to improve the optical path and absorption. In addition, the optical texture of TCOs can be easily controlled by depositing suspensions of nanostructures before the film deposition. Generally, these nanostructures are nanoparticles or even carbon nanowires or metallic nanowires (silver, copper, ...) and more recently nanowires of TiO2 (presenting the disadvantage of the titanium element) or of undoped ZnO which unfortunately decrease the conductivity due to the increase of the interface resistance with the concentration of the nanoparticles.Therefore, we propose the study of FTO thin films, pure and also in the presence of ZnO and AZO nanofibers by electrospinning from a PVA-based solution in order to have a nanostructured layer with improved transparency and electrical conductivity properties to be integrated as transparent electrodes in photovoltaic cells, meeting the performance criteria defined above. With the characterization techniques available in the LMOPS laboratory and the University of Lorraine (SEM, Raman, EDX, DRX, UV-vis Spectro, ATG, AFM, profilometer) the growth will be followed by morphological and structural studies of the layers. Finally, electrical and optical properties, in particular absorption and scattering factor, will also be extensively investigated on selected layers with the best structural and morphological properties and the minimum of interface defects when deposited on a PV structure
Abeywickrama, Thulitha Madawa. "Metal-Organic Hybrid Nanocomposites For Energy Harvesting Applications". TopSCHOLAR®, 2016. http://digitalcommons.wku.edu/theses/1748.
Texto completo da fonteThiagarajan, Suraj Joottu. "Thermoelectric properties of rare-earth lead selenide alloys and lead chalcogenide nanocomposites". Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1196263620.
Texto completo da fonteRepa, Kristen Lee Stojak. "Confinement Effects and Magnetic Interactions in Magnetic Nanostructures". Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6573.
Texto completo da fonteMayne-L'Hermite, Martine. "Elaboration, microstructure et comportement au fluage de nanocomposites Si3N4/SiC". Limoges, 1997. http://www.theses.fr/1997LIMO0021.
Texto completo da fonteRebuttini, Valentina. "Functional iron oxide-based hybrid nanostructures". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2014. http://dx.doi.org/10.18452/17049.
Texto completo da fonteThis thesis describes diverse approaches of chemical functionalization as a general strategy to tailor material properties depending on the target application. Particular attention was dedicated to the surface chemistry of iron oxide nanoparticles. Crystalline 10 nm-sized magnetite nanoparticles synthesized through the “benzyl alcohol route” exhibit superparamagnetic behaviour. For this reason they are regarded as suitable solid supports for the fabrication of recoverable devices, which is a fundamental requirement for several of the reported studies. Here it is demonstrated, via the fabrication of novel hybrid materials, that the ease of functionalization of iron oxide nanoparticles renders this material a versatile platform for the development of diverse surface chemistries. A covalent organic functionalization strategy was developed for the synthesis of two recoverable magnetic molecular receptors. The first targeted the recognition of drugs metabolites and biomarkers. It is based on the use of organosilanes coupling agents. A second approach aimed to the heterogeneous resolution of a racemic mixture of an inherently chiral cavitand. Graphene oxide-iron oxide composites were successfully fabricated through an ex-situ approach based on non-covalent interactions between the component phases. The effects of surface functionalities on the loading and distribution of iron oxide nanoparticles were studied by introducing selected functionalities at the graphene oxide surface through diazonium chemistry. Finally, the development of a non-aqueous one-pot synthesis route to gold-iron oxide hetero-nanostructures was described. Particular emphasis was dedicated to study the influence of small organic molecules in promoting the formation of the heterostructures.
Isa, Michaël. "Etude du mécanisme de nanostructuration oxydante de ZrAu : application à la synthèse de nanocomposites or-zircone pour microcapteurs de gaz". Toulon, 2003. http://www.theses.fr/2003TOUL0011.
Texto completo da fonteThe study of ZrAu alloy allowed to determine its cristallographic structures, to study its ultrafast oxidation kinetic under air and at 25°C, and to consider catalytic application as microsensors. For T>569°C, ZrAu is a CsCI superstructure. For 400
Zaitsev, Andrii. "Exploration de la voie plasma pour la synthèse de nanostructures et de nanocomposites à base de polyaniline". Thesis, Le Mans, 2015. http://www.theses.fr/2015LEMA1014/document.
Texto completo da fontePolymer nanostructures are of great interest due to their unique properties such as high shape factor. This property is essential for applications where surface interactions are involved. One example of such an application is the gas detection. Polyaniline (PANi) has been shown as a promising material for ammonia detection. Conventional synthesis (chemical orelectrochemical) of PANi nanofibers has been widely described in the literature but this way has many drawbacks. They include several steps (synthesis, purification, deposition on the substrate) and the use of chemicals (oxidants, acids) which are not environmentally friendly. The polymerization assisted by cold plasma (PECVD) allows overcoming it, as only themonomer is used and is directly polymerized on the substrate. This thesis work aims to develop plasma polyanilinenanostructures while retaining the monomer unit in the polymer. The key parameter that determines thenanostructuring process is the discharge power. At high power, highly structured films are obtained but the monomer molecules are totally fragmented. On the contrary, low power allows conservation of the monomer unit but no surface structuring is observed. We developed a method which combines the advantages of each regime. This "bottom-up" process consists to vary the input power during deposition in two or three stages. Parameters influencing the chemical and morphological structures are determined and the two and three steps methods are compared. Furthermore, the "top-down" synthesis of nanostructures by etching the PANi layer is also studied according to the plasma parameters (power and discharge time, etching gas flow rate and substrate bias). Finally, in plasma phase, we synthesized nanocomposite by combining PANi nanostructures and sputtered Pd particles. The chemical structure of the PANi films is characterized by UV-Vis spectroscopy, FT-IR and XPS. In order to highlight the nanostructuring of thin films, SEM and AFM microscopy areused. The latter one allows also the calculation of the roughness and specific surface of the PANi. EDX spectroscopyis used to bring out the presence of palladium and to quantify it. Finally, the obtained layers are characterized under gas byabsorbance variation measurements in order to determine their sensitivity and response time to ammonia
Dubois, Jean-Baptiste. "Conducteurs nanocomposites métalliques élaborés par déformation plastique sévère : formation et stabilité thermo-mécanique des nanostructures, propriétés induites". Poitiers, 2010. http://theses.univ-poitiers.fr/26782/2010-Dubois-Jean-Baptiste-These.pdf.
Texto completo da fonteThis thesis concerns the study of metallic nanocomposite copper/niobium (Cu/Nb) wires, combining high electrical conductivity and high strength, as required for the design of high magnetic field resistive coils. The reinforced continuous nanocomposite Cu/Nb conductors are fabricated via a severe plastic deformation process (SPD), which consists in repeated extrusion, drawing and bundling cycles (Accumulative Drawing and Bundling : ADB) and leads to the nanostructuration of the Nb reinforcements and a multi-scale Cu matrix. In order to optimize the process, the effect of heat treatments on texture and its development during the process were analysed by means of laboratory X-ray diffraction. Complementary in-situ heat treatments under synchrotron radiation gave a better insight into the elementary annealing mechanisms and enabled defining optimized heat treatments. These experiments also revealed that the thermal stability of Cu/Nb conductors is extremely dependent of the microstructure size: recovery, recrystallization, grain growth and all relaxation processes are frustrated in the case of nanocomposites. From these results, optimized “co-axial” conductors reinforced by Nb nanofilaments and nanotubes were processed. Their microstructure and physical properties have been characterized and compared to those of previous Cu/Nb nanocomposite conductors. With the possibility to produce long wires with improved properties, these new Cu/Nb nanocomposites offer a great alternative to existing conductors for future high magnetic field applications
Aldroe, Hanaya. "Analyse des propriétés physiques et mécaniques des nanocomposites polyamide 12 / cloisite® 30B en lien avec leurs nanostructures". Thesis, Tours, 2014. http://www.theses.fr/2014TOUR4034/document.
Texto completo da fonteNanocomposites are interestingly growing since their development in the 1990s by Toyota Company. Therefore, improving the properties of such materials is a major issue from fundamental and industrial point of view. This improvement can pass through a relevant choice of reinforcing loads added to the matrix particularly regarding the type, geometry, the proportion, and the treatment of these fillers. The processing parameters of the mixture play also a key role. The objective of this work is to contribute to the identification and understanding of the mechanisms at the origin of the reinforcing thermoplastic matrices by nanofillers. This aspect presented through the study of the thermal and mechanical properties of nanocomposites formed by a polyamide 12 matrix (PA12) filled with organically modified clay nanoparticles. More specifically, we analysed the effects of the filler mass fraction and environmental aging on structural, thermal and mechanical properties of these nanocomposites. The mixing conditions on these properties were also examined. A particular attention has been paid to the study of relationships between the macroscopic properties and the structure of nanocomposites. Viscoelastic properties of these materials in both melt and solid states were compared, which represents one of the originalities of this work
Gupta, Maneesh Kumar. "Stimuli-responsive hybrid nanomaterials: spatial and temporal control of multifunctional properties". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45920.
Texto completo da fonteGonzato, Carlo. "Chemical nanosensors based on molecularly imprinted polymer nanocomposites synthesized by controlled radical polymerization". Compiègne, 2012. http://www.theses.fr/2012COMP2035.
Texto completo da fonteMolecularly imprinted polymers (MIPs) are synthetic receptors, also known as antibody mimics, that can specifically bind target molecules. Molecular imprinting has emerged, over the last 30 years; it is an extremely versatile strategy for synthesizing networks possessing high affinity and selectivity for a chemical species, used as a molecular template during their synthesis. The wide variety of materials and formats that are accessible through this strategy has resulted in a broad spectrum of applications for such MIPs, ranging from separation to sensing, catalysis, drug delivery, etc. Since the beginning, the great majority of the imprinted networks has been synthesized by assembling vinyl monomers via free-radical polymerization (FRP). This polymerization method represents a convenient choice for synthesizing MIPs, due to its easy setup, versatility, tolerance with respect to many solvents and functional groups. However, some drawbacks greatly affect the possibility of achieving of suitable degree of control over some “polymeric” parameters which become important for specific applications. The introduction of controlled/”living” radical polymerization (CRP) techniques has then represented an opportunity for MIPs to reduce, and in some cases even to overcome, some of their limits arising from FRP. In this respect, this Ph. D. Thesis has studied how the use of RAFT polymerization, one of the most applied CRPs, can be advantageously used to syntheze MIPs. This has been done by focusing on the main characteristics of CRPs: their living and controlled nature. The living nature has been exploited during the first part of this work, which involved the synthesis of superparamagnetic molecularly imprinted nanocomposites via surface-initiated RAFT polymerization of p(EGDMA-co-MAA) on amino-modified Fe3O4 nanoparticles. The polymer grafting has been performed using an unusual stirring technique (i. E. Ultrasonication) during the polymerization step, and by testing different polymerization solvents for evaluating their effect on the composite structure. It has been observed that the grafting resulted in homogeneous polymer layers, the thickness of which could be controlled by adjusting the RAFT/radical source ratio. Moreover, the living nature of RAFT fragments has been exploited for post-functionalizing the surface of a composite particle with p(EGMP) brushes, thus demonstrating the potential of fine-tuning the particle surface properties through the living chain ends. In the second part of the thesis, an in-depth study has been performed on the effects induced by the use of controlled (RAFT) polymerization conditions on the binding behaviour and structural parameters of bulk acrylic and methacrylic MIPs and the corresponding non-imprinted polymers, synthesized by RAFT and FRP with varying cross-linking degree. This strategy actually provided scaffolds with progressively increased degree of flexibility (especially in the case of acrylics) which allowed visualize the enhancement of binding and structural differences arising from the polymerization technique. As a result, it has been observed that the use of controlled (RAFT) conditions induced, on the imprinted networks, an increased template affinity over equivalent FRPs, and it has been demonstrated that this improved affinity can be related to more homogeneous distributions of the cross-linking points achieved during RAFT polymerization. The third part presents preliminary results toward the synthesis by RAFT of individual multi-composite MIP nanosensors using enhanced Raman spectroscopy (SERS) for detection
Hoang, Minh Tuan. "Modélisation et simulation multi échelle des effets de taille et des couplages électromécaniques dans les nanostructures". Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1074/document.
Texto completo da fonteNanostructures, and more specifically semiconductor nanowires, have drawn special attention in recent years for many applications such as energy harvesting systems or sensors of very high precision. Many recent experiments and theoretical ab-initio calculations have evidenced size effects, which can significantly modify the electromechanical properties of nanowires for diameters below 10 nm. The objective of this thesis is to provide multi-scale modeling of electromechanical properties of nanostructures, such as ionic nanowires and laminated nanocomposites, to reproduce the size effects associated with nanoscale in a continuum model, based on ab-initio calculations to identify and validate the models. In a first part, the surface effects in isolated homogeneous piezoelectric nanowires are modeled. A multi-scale approach is developed, including continuous nanowires modeling taking into account an additional surface energy in the piezoelectric laminates where the associated parameters are identified by ab-initio calculations. For this, a procedure based on slabs is developed, allowing through first-principles calculations on successive slabs thicknesses to isolate the surface energy and to deduce the surface elastic and piezoelectric coefficients. The equations of the continuous model are then solved by a finite element method including appropriate surface elements. The continuous multi-scale model is compared with ab-initio calculations involving full atomistic models of nanowires with different diameters (from 0.6 to 3.9 nm) to validate model regarding size effects of electromechanical properties. In the second part, multi-scale models are constructed to describe the size effects for heterogeneous nanostructures. These structures include coated nanowires or laminated nanocomposites. For nanowires with radial heterogeneity, the previously developed approach is extended to the case of coated surfaces, and involves a continuous surface energy incorporating the effects of the coating. For laminated AlN/GaN nanocomposites, size effects observed by ab-initio calculations are caused by the presence of the interfaces and induce size-dependent elastic properties with respect to the layer thickness. A continuum model based on an imperfect interface is proposed to describe the size dependent effective elastic properties of the overall composite, which are identified by ab-initio calculations. In the last part, nanogenerators system based on nanowires are modeled, involving nanowires arrays aligned in polymer substrates with graphene electrode. The previously developed finite element models are used to simulate the electromechanical properties of such systems
Budimir, Milica. "Modification of carbon nanocomposites by electromagnetic irradiation for biomedical application". Thesis, Lille 1, 2020. http://www.theses.fr/2020LIL1I050.
Texto completo da fonteMicrobial contamination is a very important issue worldwide which affects multiple aspects of our everyday life: health care, water purification systems, food storage, etc. Traditional antibacterial therapies are becoming less efficient, because inadequate use and disposal of antibiotics have triggered mutations in bacteria that have resulted in many antibiotic-resistant strains. Therefore, it is of great importance to develop new antibacterial materials that will effectively combat both planktonic bacteria and their biofilms in an innovative manner. In this context, the goal of this thesis was to develop two different carbon/polymer nanocomposites (reduced graphene oxide/polyethylenimine and carbon quantum dots/polyurethane) which exhibit excellent antibacterial properties through two different effects: photothermal and photodynamic. Electromagnetic irradiation was used (near-infrared laser radiation or gamma rays) in these experiments, for the purpose of triggering the photothermal effect and enhancing the photodynamic effect of the nanocomposites. In the first experimental part of this thesis, a simple and efficient strategy for bacteria capture and their eradication through photothermal killing is presented. The developed device consists of a flexible Kapton interface modified with gold nanoholes (Au NH) substrate, coated with reduced graphene oxide-polyethyleneimine thin films (K/Au NH/rGO-PEI). The K/Au NH/rGO–PEI device was efficient in capturing and eliminating both planktonic Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) bacteria after 10 min of NIR (980 nm) irradiation. Additionally, the developed device could effectively destroy and eradicate Staphylococcus epidermidis (S. epidermidis) biofilms after 30 min of irradiation. In the second experimental part, the preparation of a hydrophobic carbon quantum dots/polyurethane (hCQD-PU) nanocomposite with improved antibacterial properties caused by gamma-irradiation pre-treatment is presented. Hydrophobic quantum dots (hCQDs), which are able to generate reactive oxygen species (ROS) upon irradiation with low power blue light (470 nm), were incorporated in the polyurethane (PU) polymer matrix to form a photoactive nanocomposite. Different doses of gamma irradiation (1, 10 and 200 kGy) were applied to the formed nanocomposite in order to modify its physical and chemical properties and improve its antibacterial efficiency. The pre-treatment by gamma-irradiation significantly improved antibacterial properties of the nanocomposite, and the best result was achieved for the irradiation dose of 200 kGy. In this sample, total bacteria elimination was achieved after 15 min of irradiation by blue light, for Gram-positive and Gram-negative strains
Shi, Yupeng. "Functionalized Silica Nanostructures : Degradation Pathways and Biomedical Application from 2D to 3D". Electronic Thesis or Diss., Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2018SORUS122.pdf.
Texto completo da fonteSilica nanoparticles, thanks to the great easy and adaptability of particle synthesis and limited biotoxicity, is very widely studied for biomedical applications. This thesis conducted a large diversity of investigations involving silica nanomaterials. Firstly, the physicochemical properties and biodegradation properties of three types of structured silica nanoparticles were studied in a buffer, a culture medium and in contact with human dermal fibroblasts that suggest that, under these conditions, the silica nanoparticles must be mainly considered as degraded by hydrolysis and not biodegraded. Then, multifunctional silica nanoparticles which are consist of hollow silica nanoparticles and MnO2 nanosheets were synthesized. And the control drug release and imaging performance of this nanoplatforms were studied from 2D to 3D models. This approach could be used for a rapid assessment of the biofunctionality of nanoparticles before setting up in vivo experiments. Furthermore, a new 3D collagen-based nanocomposites using silica rods were studied and the relationships between the composite composition, structure and mechanical properties, emphasizing the key role of collagen-silica interactions. The influence of these parameters on the adhesion and proliferation of fibroblast cells was also investigated. In addition, we prepared and used magnetic silica nanorods to control particle orientation within the collagen network thanks to an external magnetic field. All the results bring new insights on the preparation and properties of bionanocomposites and open the route to multifunctional hydrogels
Sauvage, Xavier. "Transformations de phases induites par déformation plastique intense. Cas des aciers perlitiques tréfilés et des nanocomposites filamentaires Cu/Nb". Rouen, 2001. http://www.theses.fr/2001ROUES032.
Texto completo da fonteAdireddy, Shivaprasad Reddy. "High Yield Solvothermal Synthesis of Hexaniobate Based Nanocomposites via the Capture of Preformed Nanoparticles in Scrolled Nanosheets". ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1726.
Texto completo da fonteMatsumura, Masashi. "Synthesis, electrical properties, and optical characterization of hybrid zinc oxide/polymer thin films and nanostructures". Birmingham, Ala. : University of Alabama at Birmingham, 2007. https://www.mhsl.uab.edu/dt/2009r/matsumura.pdf.
Texto completo da fonteTitle from PDF t.p. (viewed Feb. 3, 2010). Additional advisors: Derrick R. Dean, Sergey B. Mirov, Sergey Vyazovkin, Mary Ellen Zvanut. Includes bibliographical references (p. 122-145).
Laurent, Christophe. "Contribution à l'étude de nanocomposites à matrice céramique. Alumine-alliages fer-chrome et alumine-zircone-fer et alliages fer-chrome". Toulouse 3, 1994. http://www.theses.fr/1994TOU30017.
Texto completo da fonteKintz, Harold. "Réalisation de couches minces nanocomposites par un procédé original couplant la pyrolyse laser et la pulvérisation magnétron : application aux cellules solaires tout silicium de troisième génération". Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00958453.
Texto completo da fonteKim, Kwang-Hyon [Verfasser], Thomas [Akademischer Betreuer] Elsässer, Alejandro [Akademischer Betreuer] Saenz e Claus [Akademischer Betreuer] Ropers. "Ultrafast nonlinear optical processes in metal-dielectric nanocomposites and nanostructures : passive mode-locking, slow light, high harmonic generation / Kwang-Hyon Kim. Gutachter: Thomas Elsässer ; Alejandro Saenz ; Claus Ropers". Berlin : Humboldt Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://d-nb.info/1021720437/34.
Texto completo da fonteThilly, Ludovic. "Exploration theorique et experimentale de fils nanocomposites continus presentant des proprietes extremes de conductivite electrique et de limite elastique : application future : Coilin 100 t". Toulouse, INSA, 2000. http://www.theses.fr/2000ISAT0028.
Texto completo da fonteBarin, Gabriela Borin. "Preparação e caracterização de nanoestruturas de carbono por método hidrotérmico a partir de biomassa". Universidade Federal de Sergipe, 2011. https://ri.ufs.br/handle/riufs/3511.
Texto completo da fonteNanostructured carbon materials production can constitute an alternative for a sustainable management of residues originated from petrochemical waste and agriculture activities, toward the development of multifunctional ―green‖ materials. The coconut processing industry generate a significant amount of waste (45% of mass). The shell, fibers and coconut coir dust have been studied extensively to produce conventional carbon materials. The goal of this work was to produce carbon-clay nanocomposites and carbon nanostructures by hydrothermal route. By using coconut fiber residue as carbonaceous precursor along with lamellar (montmorillonite and kaolinite) and fibrous clays (sepiolite and attapulgite).The obtained materials were characterized by X-ray diffraction, Raman and Infrared spectroscopy, thermogravimetry, scanning and transmission electron microscopy and area and porosity measurements by BET. Carbon phase formation was indicated by infrared results with bands at ~ 1444 cm-1 and ~ 1512 cm-1 assigned to C=C of aromatic groups. Raman spectroscopy results showed presence of carbonaceous species by the appearance of D and G bands assigned to disordered and graphitic crystallites, respectively. The estimated particle size based on Raman bands was found between 8-33 nm. SEM results showed that the morphology of coconut coir dust was preserved and all materials showed overlapping sheets and plates formation. In transmission electron microscopy (TEM) images it was possible to observe three types of carbon nanostructures: sheets, fibers and nanoparticles. It was observed the formation of very thin amorphous sheets, as well as the presence of partially ordered graphitic domains and disperse carbon nanoparticles.
A produção de materiais de carbono nanoestruturados pode constituir uma alternativa para a reutilização de resíduos provenientes da indústria petroquímica e atividades agrícolas, abrindo um caminho para o desenvolvimento de materiais ―verdes‖ multifuncionais. Da indústria do processamento do coco, origina-se uma quantidade significativa de resíduos (45% do fruto). A casca, fibras e pó de coco são estudados extensivamente para a produção de materiais de carbono convencionais. A proposta deste trabalho foi produzir nanocompósitos de carbono-argila e nanoestruturas de carbono, via rota hidrotérmica. Para tanto foi utilizado o pó de coco in natura como precursor carbonáceo e argilas lamelares (montmorillonita e caulinita) e fibrosas (atapulgita e sepiolita). Os materiais obtidos foram caracterizados por difração de Raios-X, espectroscopia Raman e no Infravermelho, Termogravimetria, Microscopia eletrônica de Varredura (MEV) e Transmissão (MET), e medidas de área superficial e porosidade por BET. A formação de carbono foi indicada pelos resultados de infravermelho com bandas em ~1444 cm-1 e ~1512 cm-1 atribuídas a C=C de grupos aromáticos. Os resultados de espectroscopia Raman evidenciaram a presença de espécies carbonáceas pelo aparecimento das bandas D e G atribuídas, respectivamente, a presença de desordem e cristalitos de grafite. A faixa de tamanho de partícula estimada a partir das bandas Raman está entre 8-33 nm. Os resultados de MEV mostraram que a morfologia do pó de coco foi preservada e todos os materiais obtidos apresentaram a formação de folhas sobrepostas e placas. Nas imagens de microscopia eletrônica de transmissão (MET) foi possível observar a formação de três tipos de nanoestruturas de carbono: folhas, fibras e nanopartículas. Observou-se a formação de folhas muito finas, de caráter predominantemente amorfo, bem como a presença de domínios grafiticos parcialmente ordenados, e nanopartículas de carbono dispersas.
Stolk, Jonathan Douglas. "Development of low thermal expansion, high conductivity nanocomposites /". Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
Texto completo da fonteIşık, Kıvanç Tanoğlu Metin. "Layered silicate/polypropylene nanocomposites/". [s.l.]: [s.n.], 2006. http://library.iyte.edu.tr/tezler/master/makinamuh/T000532.pdf.
Texto completo da fonteYe, Yueping. "Microstructure and properties of epoxy/halloysite nanocomposite /". View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?MECH%202006%20YE.
Texto completo da fonteYang, Yong. "Carbon dioxide assisted polymer micro/nanofabrication". Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1117591862.
Texto completo da fonteTitle from first page of PDF file. Document formatted into pages; contains xviii, 226 p.; also includes graphics (some col.). Includes bibliographical references (p. 206-226). Available online via OhioLINK's ETD Center
Maniar, Ketan K. "A literature survey on nanocomposites". Full text available online (restricted access) Full text available online (restricted access), 2002. http://images.lib.monash.edu.au/ts/theses/maniar.pdf.
Texto completo da fonteSemaan, Chantal. "Polymères nanostructurés à base de nanotubes de carbone". Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14187/document.
Texto completo da fonteThis work is concerned with the study of carbon nanotubes (CNT) dispersions in a polymer matrix in order to obtain nanocomposite with unique properties. In the first part, we investigated the CNT wrapping by amphiphilic block copolymers to facilitate their suspension in aqueous solution. Based on the results, we could assess the effect on CNT dispersion quality of the molar mass of copolymers, the nature of the hydrophobic block and the length of hydrophilic block. In the second part, the incorporation of CNTs in polymer matrix was developed. Water or melt processing were chosen to control the distribution of CNTs in various polymer matrices (Polyethylene oxide, polyethylene and polymethyl methacrylate) through a prior wrapping of CNT. The studies of physical properties, including rheological and electrical properties, of nanocomposites were undertaken. Relationships between the state of dispersion, the nature of the coating and the method of preparation of composites were established
Brown, Elvie Escorro. "Bacterial cellulose/thermoplastic polymer nanocomposites". Online access for everyone, 2007. http://www.dissertations.wsu.edu/Thesis/Spring2007/e_brown_050207.pdf.
Texto completo da fonte